I wouldnt worry too much about your exam I'm sure there will be a resit policy, but chances are you will pass first time just fine. I don't necessarily agree though that if you don't pass on 2nd time you're in the wrong career, some people take longer to retain information. In fact there is a lot of evidence that shows that exams are not the best way to prove someones knowledge anyway.
My advice to you as a qualified teacher is to make up a mock exam paper of questions you think might be asked, photocopy or print it out several times and every so often do the exam paper. Ask your educator for their input, thats what they are there for. I recently had to learn over 35 different reflex points on the feet and so I photocopied a foot and drew the points on, doing it over and over worked wonders for me. But then again it might not be for you, everyone is different, but I find re-answering questions helps me to retain information.
Hope that helps and good luck!!